Why can't I sync with my Google account?

Moto G3 3rd Generation running Android 6.0
My Contacts and Calendar will not sync with my Google account. I've tried everything I can think of to fix it, including removong/re-adding the Google account, clearing data, clearing cache, clearing the cache partition. When I tap Accounts - Google - then tap Sync Now from the 3 dots icon, I see the message "Sync is currently experiencing problems. It will be back shortly". But it never comes back. Although the Calendar shows a last synced date and time there is no calendar data at all in the Calendar app. The Contacts also show a last synced date and time but there are no Contacts in the Contacts app except for me. What steps can I take to make the sync operation work? Thanks very much.